GREENER PASTURES

By Peter Warren, Extension Agent
Published: August 28, 2008

One of the most popular landscape plants in Virginia and parts south is the crapemyrtle (Lagerstroemia indicia L.). There are many cultivars of size ranging from 5 to 35 feet in height and offering long-lasting flowers of white, pink, purple, or red. Some cultivars also sport beautiful gray/cinnamon brown exfoliating bark. They are relatively easy to grow and except for an occasional hard winter seem to do fine in our zone 7 climate.
They can be purchased in containers or as balled and burlapped. They like moist, well-drained soil and full sun. The main problems they suffer from are powdery mildew, leaf spot, and aphids (and the resulting sooty mold that develops on their honeydew excretion). Careful pruning and judicious use of fungicides can keep these problems to a minimum in most years. In addition there are cultivars that are more or less susceptible to powdery mildew. 
Crapemyrtle bloom time varies by cultivar but you can usually expect flowers from summer into fall. If you purchase a blooming plant in summer to verify the color of the blooms make sure to give it lots of care after planting since summer is a stressful time of year to get established. Light pruning of old blooms or seedpods will encourage a second flush of flowers later in the summer or fall.
An unfortunate but common practice is the topping or heavy pruning of these plants often called “crape murder” because of the harmful effects it causes. I often see them cut back in leaving only short trunks sticking out of the ground. This practice destroys the natural shape of the tree and causes multiple shoots to sprout from each cutback point. Trees then grow so thick that air circulation is reduced, making the plants more susceptible to aphids, powdery mildew, and sooty mold. The numerous branches also create too heavy a load, which can cause them to split or crack during heavy rains and high winds. Even if the long, thin branches put out by the murdered crapemyrtle do not break off, these new branches are often too weak to hold up their flowers in the normal position, causing the limbs to droop over with the weight of the flowers and seedpods. Finally, anytime you top a tree you are causing great stress to the tree and making it susceptible to insects and diseases that it would normally be able to withstand. 
Doing this hard pruning simply to get more flowers has limited results. There may be more flowers the first time because the crapemyrtle will put out multiple branches for every branch that got cut. By keeping this practice in subsequent years, there will continue to be the same number of spindly branches each year (minus the ones that split and fell over). If the tree is allowed to grow naturally, it will continue to develop, creating a larger canopy each year with each branch putting out more flowers. 
Crapemyrtles grow beautifully when allowed to grow on their own. As with all trees, they may need some selective pruning to help enhance their shape and symmetry and remove damaged or rubbing limbs, but this is nothing like cutting them in half or more each year. The branching structure can be very nice to look at in the winter as well, and when they leaf out in the spring, the tree has a much more balanced look rather than the bushy growth at the end of thick stubs you see after harsh pruning.
It is important to know the mature height of any shrub or tree before you plant it. Crapemyrtles are sold in various size categories: Miniatures (18-36"), Dwarf (3-5’), Semi-dwarf (5-12’), Intermediate (13-20’), and Standard or tree form (23-25’).
Trees such as Natchez, Choctaw, and Tuscarora reach 25-30 feet. “Apalachee” and “Sioux” are intermediate at 13-20 feet tall, and “Hopi” and “Zuni” are semi-dwarf selections that will only grow 5-12 feet tall. For a nice 5-foot tree, try “Velma’s Royal Delight” or “Catawba.”